There are known in the prior art various high-speed printing devices which print by applying to the medium to be printed a plurality of dots of printing material in the configuration of one or more characters to be applied to the medium. One of the most common types of such high-speed printers is a matrix printer using a plurality of reciprocating wires which are driven in an axial direction to impinge on a carbon ribbon or the like in front of paper so as to produce a dot pattern on the paper. Such printers embody a number of disadvantages. First, the wires must be recocked after each operation and the time taken to perform the recocking is lost time. Secondly, for reasonable resolution the wire diameter must be kept small and the wires themselves must be supported near the paper surface. Individual bearings for the wires result in a fixed X, Y position for each wire. With such a printer, it is not possible to produce overlapping dots without moving the printing head relative to the medium. The system thus inherently is limited as to the quality of character which can be produced thereby without such relative motion. In addition, owing to the fact that each of the individual wires has its own bearing, the device is relatively large and is expensive.
Another type of high-speed printer known in the prior art is the so-called "ink-jet" printer in which jets of ink are propelled onto the printing medium. These printers likewise incorporate a number of disadvantages. Owing to the fact that one cannot accurately propel a drop of liquid over an appreciable distance, the size of the character which can be produced is limited. In addition, the flight path of the jet is sensitive to ambient air currents. Problems of splattering and splashing also are present. Thus, the quality of the characters produced by such a system varies widely. A major disadvantages of an ink-jet printer is that it cannot make carbon copies.